<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
            /* box-sizing: border-box; */
        }
        html,body{
            width: 100%;
            height: 100%;
        }
        header,footer{
            background-color: rgb(180, 178, 178);
            height: 100px;
            clear: both;
        }
        .content{
            /* 减号左右有空格 */
            height: calc(100vh - 200px);
            display: flex;
            flex-wrap: nowrap;
        }
        /* .content div{
            height: 300px;
        } */
        .center{
            background-color: aqua;
            flex: 1;
            order: 1;
        }
        .left{
            background-color: aquamarine;
            width: 200px;
            order: 0;
        }
        .right{
            background-color: bisque;
            width: 300px;
            order: 2;
        }
    </style>
</head>
<body>
    <header >头部</header>
    <div class="content">
        <div class="center">中间</div>
        <div class="left">左边</div>
        <div class="right">右边</div>
    </div>
    <footer>尾部</footer>
    
</body>
</html>